The present invention relates to body-worn mobile hearing devices, such as head-worn hearing aids and personal sound amplifier products (“PSAPs”) which are powered by one or more batteries. In particular, the present invention pertains to such hearing devices which have the capacity to wirelessly stream real-time audio content, such as disclosed in U.S. Pat. No. 9,832,578, incorporated by reference.
Today's hearing devices are increasingly technologically advanced to improve the overall experience of the user, in some cases including integrated wireless systems. In one aspect, an on-board integrated wireless system can enable commands and programming data to be wirelessly communicated to the hearing device, such as via Bluetooth Low Energy (“BLE”) for changing various settings or programs of the digital signal processor. Such hearing devices should be designed to use as little electrical power as possible and to conserve battery life for as long as possible, typically while using a battery which is quite small and lightweight.
When using BLE, all BLE radio activity, whether it is an advertisement or a connection event, happens in regular time intervals, that is, repeatable time frames. The BLE specification allows these regular time intervals to having a spacing which can be selected front 7.5 ms to 4 secs (with increments of 1.25 ms). The key to BLE's power savings is the duty cycle, or time comparison between the length of the connection event (the actual transmission Tx and/or reception Rx of wirelessly transmitted data, typically at higher current draws) and the connection interval. In some real world applications, such as sending settings of the digital signal processor of a hearing aid or PSAP, the connection event (Tx and/or Rx) is often a 300 μs maximum activity duration within a 500 ms connection interval, which corresponds to 0.06% duty cycle. During the majority of the 500 ms connection interval, there is little or negligible current draw for the radio components, commonly referred to as a “sleep” mode. When the microcontroller and radio components are “asleep”, power is turned off (such as via one or more phase-locked loop (“PLL”) type switches) to inactivate certain sections of the processor silicon, so no power is consumed therein until the wake-up trigger executes.
In terms of overall battery usage of the hearing aid, radio operation uses a significant percentage of battery power. Moreover, even though the advertising/connection event (Tx and/or Rx, which may be limited to lasting 300 μs or less) involves peak power consumption of the radio, significant power usage occurs at lower power levels immediately before and/or after (such as within 50 ms before or after) the actual advertising/connection event while not in sleep mode. For each wireless radio event, the processor is turned on, the radio front-end may be ramped up before the event and ramped down after the event, and various post-processing activities may be performed after the event. With battery drainage being critical to successful hearing device implementation, the radio usage and all associated processing should be undertaken to preserve as long of battery life as possible. Better solutions are needed.